Universal multipurpose sensor fixing device

ABSTRACT

A universal multipurpose sensor fixing device comprises a radial positioning mechanism, supporting mechanisms, bases, acoustic emission test sensor mounting mechanisms, and parallelism adjusting members. Each supporting mechanism includes a main arm and an auxiliary arm having one end connected to the main arm and a ball head on the other end. A parallelism adjusting member mounting mechanism is provided at the joint of the main arm and the auxiliary arm. The main arms are respectively connected to the two free ends of the radial positioning mechanism to position the auxiliary arms at the inner sides of the main arms, arranged axis symmetrically with respect to the central line of the radial positioning mechanism. The ball heads of the two auxiliary arms are located within spherical holes of the bases to form universal revolute pairs. A set of acoustic emission test sensor mounting mechanisms are mounted at each base.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/689,785, filed Jan. 19, 2010, which claims priority to ChineseApplication No. 200910059593.8, filed Jun. 15, 2009. The entiredisclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an acoustic emission test sensor fixingdevice used in columnar test piece experiment and test of materials suchas rock and concrete.

BACKGROUND OF THE INVENTION

In rock mechanical experiments, when acoustic emission features of rockdamage process and etc. are tested, the acoustic emission test sensorscurrently used do not have specific fixing devices, and two fixingmethods of winding with rubber belt and fastening with bungee arecommonly adopted in current experiments and tests. Acoustic emissiontest sensors generally have a diameter within the range of 5 mm to 15 mmand need to couple tested members using media such as a gel, butter,vaseline and etc. as a coupler, which result in that the fixing methodsof winding with rubber belt and fastening with bungee are unable toensure fine parallelism between the end face of the acoustic emissiontest sensor and the coupling face of the tested member and the finecoupling between the end face of the acoustic emission test sensor andthe tested member, especially, test pieces with irregular shapes makethe fixing more difficult. Also, couplers such as butter, vaseline andetc. may easily result in the adhesion reduction or failure of therubber belt, and the rubber belt may easily form great binding on theacoustic emission test sensor during radial swelling and deforming ofthe tested member, so that it undertakes increasing force and is evendamaged to some extent; for the fixing method of fastening by bungee,although the bungee is elongated by pulling during radial swelling anddeforming of tested member and may deform to some extent, this fixingmethod may easily cause the acoustic emission test sensor to tumble, andthus it is difficult to ensure fine contact between the acousticemission test sensor and the tested member. In addition, the abovementioned two fixing methods need to be performed before test pre-addingand adjustment cannot be made during the test, and it is also difficultto accurately contraposition the acoustic emission test sensor. Theabove mentioned two fixing methods also have the following problems: (1)they can hardly ensure the consistency of force to the acoustic emissiontest sensor in the same batch of tested members and may easily form manypseudo signals, thus resulting in much difficulty to analysis andjudgment of the test result; and (2) they cause the mounting of otherdeforming test sensors very inconvenient.

SUMMARY OF THE INVENTION

The present invention may provide a universal acoustic emission testsensor fixing device, to ensure fine contact between the acousticemission test sensor and the tested members with different shapes (beingregular and irregular), and improve test efficiency and the accuracy andthe truthfulness of the testing.

The universal acoustic emission test sensor fixing device according tothe present invention comprises a radial positioning mechanism,supporting mechanisms, bases, acoustic emission test sensor mountingmechanisms, and parallelism adjusting members, wherein the supportingmechanisms, the bases, the acoustic emission test sensor mountingmechanisms, and the parallelism adjusting members are all in two sets;the supporting mechanism includes a main supporting arm and an auxiliarysupporting arm, with one end of the auxiliary supporting arm beingfixedly connected to or hinged with the main supporting arm and theother end being provided with a ball head, and a parallelism adjustingmember mounting mechanism is provided at the joint of the mainsupporting arm and the auxiliary supporting arm, and the base isprovided with a spherical hole matching the ball head of the auxiliarysupporting arm. The above assemblies or members are assembled asfollows: the main supporting arms of two sets of supporting mechanismsare respectively connected to the two free ends of the radialpositioning mechanism in the way that the auxiliary supporting arms ofthe two sets of supporting mechanisms are respectively located at theinner sides of the main supporting arms and are arranged axissymmetrically with respect to the central line of the radial positioningmechanism, and the ball heads of the two auxiliary supporting arms arerespectively located within the spherical holes of the two bases to formuniversal revolute pairs, two sets of acoustic emission test sensormounting mechanisms are respectively mounted at the two bases, and twosets of parallelism adjusting members are respectively mounted on thetwo main supporting arms via mounting mechanisms provided on the mainsupporting arms.

Exemplary structures of the above assemblies constituting the acousticemission test sensor fixing device according to the present inventionare described as follows:

-   -   1. The radial positioning mechanism includes two elastomers and        one screw, and the two elastomers are respectively connected        with rigid ends at respective one end, each of said rigid ends        is provided with a screw hole matching the screw, and the screw        forms screw pairs respectively with the screw holes in the two        rigid ends; or the radial positioning mechanism only consists of        elastomers.    -   2. The base is a rectangular or circular platform and is        provided with a slot in the lower portion, and the spherical        holes matching the ball heads of the auxiliary supporting arm        are provided in the upper surface of the base; corresponding to        the structure of the base, the acoustic emission test sensor        mounting mechanism comprises a plugboard matching the slot in        the base, an acoustic emission test sensor mounting member and        an acoustic emission test sensor fixing member; the plugboard is        provided with a plugboard fixing buckle or a plugboard fixing        screw hole, and the plugboard is inserted into the slot of the        base and fixed with the base via a bolt or the fixing buckle;        the acoustic emission test sensor mounting member is a cylinder        provided with a gap and is fixedly connected with or forms a        one-piece structure with the plugboard, with its inner diameter        matching the outer diameter of an acoustic emission test sensor        (during implementation, cylinders with different inner diameters        can be made according to the acoustic emission test sensor, to        form a series of cylinders meeting the demands of testing); the        acoustic emission test sensor fixing member consists of a        circular elastic plate provided with a gap and a fastening screw        or a fixing buckle, when the acoustic emission test sensor is        mounted within the cylinder with a gap, the circular elastic        plate with a gap is put around the gap section of the cylinder,        and then the acoustic emission test sensor is fixed within the        cylinder via a fastening screw or the fixing buckle.    -   3. The base is a rectangular or circular platform and is        provided with a connecting screw hole in the lower portion, and        the spherical holes matching the ball heads of the auxiliary        supporting arm are provided in the upper surface of the base;        corresponding to the structure of the base, the acoustic        emission test sensor mounting mechanism comprises a threaded        section matching the connecting screw hole in the base, an        acoustic emission test sensor mounting member and an acoustic        emission test sensor fixing member; the threaded section is        mounted within the connecting screw hole in the lower portion of        the base and is fixedly connected via threaded connection; the        acoustic emission test sensor mounting member is a cylinder        provided with a gap and is fixedly connected with or forms a        one-piece structure with the end face of the threaded section,        with its inner diameter matching the outer diameter of an        acoustic emission test sensor, and the acoustic emission test        sensor fixing member consists of a circular elastic plate        provided with a gap and a fixing buckle or a fastening screw.    -   4. The parallelism adjusting member consists of three screws,        the parallelism adjusting member mounting mechanism provided at        the joint of the main supporting arm and the auxiliary        supporting arm consists of two mounting screw holes provided in        the main supporting arm and a mounting plate hinged with the        main supporting arm and located between the two screw holes, and        the mounting plate is provided with a mounting screw hole.

The using method for the universal acoustic emission test sensor fixingdevice according to the present invention is described as follows:

-   -   1. Determine the number of the acoustic emission test sensors        and the mounting position thereof at the tested member according        to the shape of the tested member and the object of the        experiment test, and mount the acoustic emission test sensor        within the acoustic emission test sensor fixing device;    -   2. Place the tested member between upper and lower load press        heads of a test machine, respectively, place the acoustic        emission test sensors mounted within respective acoustic        emission test sensor fixing devices at two sides of different        portions of the tested member to be tested respectively, and        attach the acoustic emission test sensors to the tested member        tightly via the radial positioning mechanism; and    -   3. Rotate the base so that the end face of the acoustic emission        test sensor mounted in the acoustic emission test sensor fixing        device is substantially parallel to the coupling surface portion        of the tested member, adjust the mounting plate hinged with the        main supporting arm to a suitable position, and then adjust the        end face of the acoustic emission test sensor via the        parallelism adjusting member so that it is substantially        parallel to the coupling surface of the tested member.

Upon conformity of mounting and adjusting of the acoustic emission testsensors with requirements, the test piece that needs to be tested can betested according to a predetermined experiment and test solution.

The present invention realizes the following advantageous effects:

-   -   1. As the ball heads of the auxiliary supporting arm form        universal revolute pairs with the spherical holes of the bases        and the radial positioning mechanism includes elastic members,        the universal acoustic emission test sensor fixing device        according to the present invention is applicable to tested        members of various shapes (being regular or irregular), and the        acoustic emission test sensor fixing device can attach the        acoustic emission test sensors tightly to the tested member        during the whole test process and keep the end face of the        acoustic emission test sensors mounted in the acoustic emission        test sensor fixing device parallel to the coupling surface of        the tested member, thereby ensuring the truthfulness of the test        result and improving the accuracy of the test result.    -   2. As the radial positioning mechanism comprises elastic        members, when the tested member swells radially in the test,        force of the acoustic emission test sensor will not be        increased, which could easily ensure force consistency of the        acoustic emission test sensor during testing for the same batch        of tested members, thereby lowering the influence of the pseudo        signals on the testing result and also improving the life of the        acoustic emission testing sensor.    -   3. The acoustic emission test sensor fixing device according to        the present invention makes it convenient to arrange the        acoustic emission test sensor at any position on the surface of        the tested member, and other deforming test sensors can be        arranged at the same time, so as to obtain more different        testing information of the tested member during the same testing        process.    -   4. Using the acoustic emission test sensor fixing device        according to the present invention, the acoustic emission test        sensor can be mounted at any period of time before or after        pre-adding contact load to the tested member, and the position        of the acoustic emission test sensor can also be adjusted during        the experiment.    -   5. The universal acoustic emission test sensor fixing device        according to the present invention is convenient in use, it can        be mounted quickly, and can improve test efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a first structure of theuniversal acoustic emission test sensor fixing device according to thepresent invention;

FIG. 2 is a schematic view illustrating a second structure of theuniversal acoustic emission test sensor fixing device according to thepresent invention;

FIG. 3 is a schematic view illustrating a third structure of theuniversal acoustic emission test sensor fixing device according to thepresent invention;

FIG. 4 is a schematic view illustrating the parallelism adjusting membermounting mechanism provided on the main supporting arm in the universalacoustic emission test sensor fixing device according to the presentinvention;

FIG. 5 is a schematic view illustrating a structure of the base in theuniversal acoustic emission test sensor fixing device according to thepresent invention and an assembling of the base and the auxiliarysupporting arm;

FIG. 6 is a top view of FIG. 5;

FIG. 7 is a right view of FIG. 5;

FIG. 8 is a schematic view illustrating a first structure of theacoustic emission test sensor mounting mechanism in the universalacoustic emission test sensor fixing device according to the presentinvention;

FIG. 9 is a top view of FIG. 8;

FIG. 10 is a schematic view illustrating a second structure of theacoustic emission test sensor mounting mechanism in the universalacoustic emission test sensor fixing device according to the presentinvention;

FIG. 11 is a top view of FIG. 10;

FIG. 12 is a schematic view illustrating another structure of the basein the universal acoustic emission test sensor fixing device accordingto the present invention and an assembling of the base and the auxiliarysupporting arm;

FIG. 13 is a top view of FIG. 12;

FIG. 14 is a schematic view illustrating a third structure of theacoustic emission test sensor mounting mechanism in the universalacoustic emission test sensor fixing device according to the presentinvention; and

FIG. 15 is a schematic view illustrating the assembling of the base inFIG. 12 and the acoustic emission test sensor mounting mechanism in FIG.14.

In the figures: 1—screw, 2—rigid end, 3—arc elastomer, 4—main supportingarm, 5—parallelism adjusting member, 6—parallelism adjusting membermounting plate, 7—auxiliary supporting arm, 8—base, 9—acoustic emissiontest sensor mounting mechanism, 10—acoustic emission test sensor,11—tested member, 12—semicircular elastomer, 13—mounting screw hole inthe parallelism adjusting member, 14—ball head, 15—slot, 16—plugborad,17—cylinder provided with gap, 18—circular elastic plate provided withgap, 19—sensor fixing buckle, 20—plugborad fixing buckle, 21—plugboardfixing screw hole, 22—sensor fastening screw, 23—connecting screw hole,and 24—threaded section.

DETAILED DESCRIPTION OF THE INVENTION

The specific structure of the universal acoustic emission test sensorfixing device according to the present invention will be furtherdetailed hereinafter in conjunction with the accompanying drawings.

Embodiment 1

In this embodiment, the structure of the universal acoustic emissiontest sensor fixing device is shown in FIG. 1, comprising a radialpositioning mechanism, supporting mechanisms, bases 8, acoustic emissiontest sensor mounting mechanisms 9, and parallelism adjusting members 5,wherein the supporting mechanisms, the bases, the acoustic emission testsensor mounting mechanisms, and the parallelism adjusting members areall in two sets.

The radial positioning mechanism, as shown in FIG. 1, comprises two arcelastomers 3 and one screw 1, and the two arc elastomers arerespectively connected with rigid ends 2 at respective one end, each ofsaid rigid ends is provided with a screw hole matching the screw, andthe screw forms screw pairs respectively with the screw holes in the tworigid ends. The supporting mechanism, as shown in FIG. 1, comprises amain supporting arm 4 and an auxiliary supporting arm 7; the mainsupporting arm 4 is made of nickel titanium alloy and has a rectangularcross section; a parallelism adjusting member mounting mechanism isprovided at the joint of the main supporting arm and the auxiliarysupporting arm, as shown in FIG. 4, the parallelism adjusting membermounting mechanism consists of two mounting screw holes 13 provided inthe main supporting arm and a mounting plate 6 hinged with the mainsupporting arm and located between the two screw holes, and the mountingplate 6 provided with one mounting screw hole 13 therein; the auxiliarysupporting arm 7 is made of nickel titanium alloy and has a circularcross section, with its one end fixed on the main supporting arm viathreaded connection and the other end provided with ball heads 14 (asshown in FIGS. 1 and 7). The base 8, as shown in FIGS. 5, 6 and 7, hasan overall shape of rectangular platform, and the base is provided witha slot 15 in the lower portion, and the spherical hole matching the ballhead of the auxiliary supporting arm is provided in the upper surface ofthe base. The acoustic emission test sensor mounting mechanism 9, asshown in FIGS. 8 and 9, comprises a plugboard 16 matching the slot inthe base, a cylinder 17 with a gap, a circular elastic plate 18 with agap and a fixing buckle 19, wherein the plugboard 16 is provided with aplugboard fixing buckle 20, the cylinder 17 is fixedly connected withthe plugboard 16 at the end without the gap, and the end thereof withthe gap is a free end, the circular elastic plate 18 provided with thegap is put around the gap section of the cylinder, and the acousticemission test sensor 10 is fixed within the cylinder 17 via the fixingbuckle 19. The parallelism adjusting member 5 consists of three screws.

The above assemblies and members are assembled as follows: the mainsupporting arms 4 of the two sets of supporting mechanisms arerespectively connected to the two free ends of the two arc elastomers 3of the radial positioning mechanism, in the way that the two auxiliarysupporting arms 7 are respectively located at the inner sides of themain supporting arms and are arranged axis symmetrically with respect tothe central line of the radial positioning mechanism; the ball heads 14of the two auxiliary supporting arms are respectively located in thespherical holes in the two bases to form universal revolute pairs; theplugboards 16 of the two sets of acoustic emission test sensor mountingmechanisms are respectively inserted into the slots 15 of the two basesand are fixed via the plugboard fixing buckles 20; and the screws makingup of the two sets of parallelism adjusting members 5 are respectivelymounted in the screw holes 13 in the parallelism adjusting membermounting mechanism provided on the two main supporting arms 4.

Embodiment 2

In this embodiment, the structure of the universal acoustic emissiontest sensor fixing device is shown in FIG. 2, comprising a radialpositioning mechanism, supporting mechanisms, bases 8, acoustic emissiontest sensor mounting mechanisms 9, and parallelism adjusting members 5,wherein the supporting mechanisms, the bases, the acoustic emission testsensor mounting mechanisms, and the parallelism adjusting members areall in two sets.

Different from embodiment 1, it is described in embodiment 2 that: 1)the radial positioning mechanism is a semicircular elastomer 12 (asshown in FIG. 2); and 2) the base 8, as shown in FIGS. 12 and 13, isprovided with a connecting screw hole 23 in the lower portion; theacoustic emission test sensor mounting mechanism 9, as shown in FIG. 14,comprises a threaded section 24 matching the connecting screw hole inthe base, a cylinder 17 provided with a gap, a circular elastic plate 18provided with a gap, and a fastening screw 22, wherein the threadedsection 24 is mounted within the connecting screw hole 23 in the lowerportion of the base and is fixedly connected with the base 8 viathreaded connection (as shown in FIG. 15), the cylinder 17 provided witha gap and the threaded section 24 form a one-piece structure, and theend of the cylinder with the gap is a free end; the circular elasticplate 18 provided with a gap is put around the gap section of thecylinder, and the acoustic emission test sensor 10 is fixed within thecylinder 17 via the fastening screw 22.

Embodiment 3

In this embodiment, the structure of the universal acoustic emissiontest sensor fixing device is shown in FIG. 3, comprising a radialpositioning mechanism, supporting mechanisms, bases 8, acoustic emissiontest sensor mounting mechanisms 9, and parallelism adjusting members 5,wherein the supporting mechanisms, the bases, the acoustic emission testsensor mounting mechanisms, and the parallelism adjusting members areall in two sets.

Different from embodiment 1, it is described in embodiment 3 that: 1)the radial positioning mechanism, as shown in FIG. 3, comprises astraight-bar elastomer 3 and a screw 1, and the two straight-barelastomers are respectively connected with rigid ends 2 at respectiveone end, with the rigid end is provided therein with a screw holematching the screw, and the screw forms a screw pair with the screwholes in the two rigid ends; 2) the auxiliary supporting arm 7 is hingedwith the main supporting arm 4; and 3) the acoustic emission test sensormounting mechanism 9, as shown in FIGS. 10 and 11, comprises a plugboard16 matching the slot in the base, a cylinder 17 provided with a gap, acircular elastic plate 18 provided with a gap, and a fastening screw 22,wherein the plugboard 16 is provided with four plugboard fixing screwholes 21 therein, and is fixed within the slot 15 in the base via abolt, the cylinder 17 and the plugboard 16 form a one-piece structure,and the end of the cylinder with the gap is a free end; the circularelastic plate 18 provided with a gap is put around the gap section ofthe cylinder, and the acoustic emission test sensor 10 is fixed withinthe cylinder 17 via the fastening screw 22.

What is claimed is:
 1. A universal acoustic emission test sensor fixingdevice, comprising: a radial positioning mechanism; a supportingmechanism including: a main supporting arm, and an auxiliary supportingarm, a first end of the auxiliary supporting arm connected to the mainsupporting arm and a second end of the auxiliary supporting armincluding a ball head; a base coupled to the auxiliary supporting arm toform a revolute member; an acoustic emission test sensor mountingmechanism mounted at the base; and a mounting mechanism mounted on themain supporting arm and located at a joint formed by the main supportingarm and the auxiliary supporting arm, the mounting mechanism mounting anadjusting member for adjusting the base relative to an object to betested, and the main supporting arm connected to a first end of theradial positioning mechanism to position the auxiliary supporting arm atan inner side of the main supporting arm and arranged axis symmetricallywith respect to a central line of the radial positioning mechanism. 2.The universal acoustic emission test sensor fixing device of claim 1,where the radial positioning mechanism comprises an elastomer thatconnects the main supporting arm to the radial positioning mechanism. 3.The universal acoustic emission test sensor fixing device of claim 2,where the elastomer comprises a rigid end that connects the mainsupporting arm to the radial positioning mechanism.
 4. The universalacoustic emission test sensor fixing device of claim 1, where the mainsupporting arm comprises a rectangular cross section and the auxiliarysupporting arm comprises a circular cross section.
 5. The universalacoustic emission test sensor fixing device of claim 1, where the basecomprises a spherical hole, formed in an upper surface of the base, thespherical hole receiving the ball head to couple the base to theauxiliary supporting arm.
 6. The universal acoustic emission test sensorfixing device of claim 1, where the acoustic emission test sensormounting mechanism comprises a plugboard that is received in a slotformed in the base to mount the acoustic emission test sensor mountingmechanism to the base.
 7. The universal acoustic emission test sensorfixing device of claim 1, further comprising: a second mountingmechanism mounted on a second main supporting arm and located at a jointformed by the second main supporting arm and a second auxiliarysupporting arm that is connected to the second main supporting arm, thesecond mounting mechanism mounting a second adjusting member foradjusting a second base relative to the object to be tested, the baseand the second base being positioned on opposing sides of the object tobe tested.
 8. A method comprising: connecting a first main supportingarm of a first supporting mechanism to a first end of a radialpositioning mechanism to cause a first auxiliary supporting arm of thefirst supporting mechanism to be arranged axis symmetrically withrespect to a central line of the radial positioning mechanism;connecting a second main supporting arm of a second supporting mechanismto a second end of the radial positioning mechanism to cause a secondauxiliary supporting arm of a second mechanism to be arranged axissymmetrically with respect to the central line of the radial positioningmechanism; connecting a first base member to the first auxiliarysupporting arm and a second base member to the second auxiliarysupporting arm to form a revolute pair for receiving an object to betested; mounting a first acoustic emission sensor to the first basemember and a second acoustic emission sensor to the second base member;and mounting a first parallelism adjusting member to the first mainsupporting arm and a second parallelism adjusting member to the secondmain supporting arm.
 9. The method of claim 8, further comprising:positioning the object to be tested between the first base member andthe second base member; and adjusting a position of the firstparallelism adjusting member to adjust a position of the first basemember with respect to the object to be tested.
 10. The method of claim9, further comprising: adjusting a position of the second parallelismadjusting member to adjust a position of the second base member withrespect to the object to be tested.
 11. The method of claim 8, where afirst end of the first auxiliary supporting arm hinged with the firstmain supporting arm and a second end of the first auxiliary supportingarm comprises a ball head, and where connecting the first base member tothe first auxiliary supporting arm includes: receiving the ball headwithin a spherical hole formed in a surface of the first base member.12. The method of claim 8, where connecting the first main supportingarm to the radial positioning mechanism includes: connecting the firstmain supporting arm to a first arc elastomer of the radial positioningmechanism.
 13. The method of claim 8, where the first base memberincludes a slot for receiving a first plugboard of a first mountingmechanism that mounts the first acoustic emission test sensor to thefirst base member and the second base member includes a slot forreceiving a second plugboard of a second mounting mechanism that mountsthe second acoustic emission test sensor to the second base member. 14.A device comprising: a radial positioning mechanism; a first mechanismattached to a first end of the radial positioning mechanism and a secondmechanism attached to a second end of the radial positioning mechanism,each of the first mechanism and the second mechanism including: a firstarm, a second arm, a first end of the second arm connected to the firstarm and a second end of the second arm including an attachment portion,the first arm connected to the first end of the radial positioningmechanism to position the second arm: at an inner side of the first arm,and arranged axis symmetrically with respect to a central line of theradial positioning mechanism, a base coupled to the second arm to form arevolute member; a first mounting mechanism connected to the base, thefirst mounting mechanism mounting an acoustic emission test sensor thatis used to test an object, and a second mounting mechanism connected tothe first arm and located at a joint formed by the first arm and thesecond arm, the second mounting mechanism mounting an adjusting memberfor adjusting the base relative to the object.
 15. The device of claim14, where the first end and the second end of the radial positioningmechanism each comprise: an elastomer that connects the first arm to theradial positioning mechanism.
 16. The device of claim 14, where thefirst end and the second end of the radial positioning mechanism eachcomprise: an elastomer that includes a rigid end that connects the firstarm to the radial positioning mechanism.
 17. The device of claim 14,where the first arm comprises a rectangular cross section and the secondarm comprises a circular cross section.
 18. The device of claim 14,where the base comprises: a spherical hole, formed in an upper surfaceof the base, the spherical hole receiving the attachment portion tocouple the base to the second arm.
 19. The device of claim 14, where thefirst mounting mechanism comprises: an elongated member that is receivedin a slot formed in the base to connect the first mounting mechanism tothe base.
 20. The device of claim 14, where the base included in thefirst mechanism and the base included the second mechanism arepositioned on opposing sides of the object and cooperate to retain theobject within the device.